The invention relates to a delta modulator comprising a feedback loop incorporating a cascade arrangement formed by a difference producer, a loop filter, a two-level quantizer, a clock pulse-controlled sampler, and a feedback path from the output of the sampler to an input of the difference producer to another input of which the signal to be coded is applied, the sequence of the difference producer and the loop filter being irrelevant.
Such a delta modulator or delta-sigma modulaor is generally known. The loop filter thereof is usually in the form of a single or a double integrator.
It has already been proposed to implement the loop filter in what are commonly referred to as oversampled delta modulators as a higher order filter, to eliminate the quantization noise in the speech band.
The invention has for its object to optimize the loop filter as regards the signal-to-quantization noise ratio at the output of the delta modulator.